MIL-B-5087 is superseded by MIL-STD-464, which says "Overpainting of structure for corrosion control prior to ensuring an electrical bond has been documented as the leading cause of poor or ineffective bonds."
MIL-STD-464 points to MIL-STD-1541 - for space systems ARP187 - electrical bonding for aviation MIL-HDBK-419 grounding, bonding, and shielding for land systems MIL-STD-1310 bonding for ship systems Brian From: Edward Price [mailto:e...@jwjelp.com] Sent: Friday, August 10, 2018 3:02 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] External toothed star washer used in earth connection I seem to recall seeing an explanation in MIL-B-5087 (likely now superseded) that a star washer was not acceptable for military grounding. The rationale was that the points of the star washer created the conductive grounding path. Since the points were fairly small, and the ground fault current was high, a fault current would be forced to flow across those tiny point-contacts. This had the danger of causing the points to melt or arc. The military preference was strongly in favor of removing the paint below a ground-point’s footprint and then using a flat washer below and above the ground lug, with a split-ring lockwasher followed by a nut. I have read recent criticism of split-ring lockwashers, with machinery people now seeming to favor something like the Nord-lock locking system. Ed Price WB6WSN Chula Vista, CA USA From: Richard Nute [mailto:ri...@ieee.org] Sent: Friday, August 10, 2018 2:46 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] External toothed star washer used in earth connection Hi Scott: For the sake of this discussion, a toothed star lock washer has two functions: (1) keep the bolt from loosening, and (2) establishing a “good” electrical connection. (One characteristic of a good and reliable electrical connection is that the contact between the two conductors is gas-tight.) A flat ring lug performs two functions, (1) flat washer and (2) means for electrical connection to the washer via a lug. The washer cannot -- by itself -- form a gas-tight connection to any other conductor. If the bolt is to be a current-carrying conductor, then a star washer must be placed between the ring lug and the bolt head to establish a gas-tight connection between the two (assuming the star has points on both sides of the washer). If the bolt goes through a metal panel and is intended to enable an electrical connection to the panel (on the other side), then another star washer must be used (on the bolt) between the nut and the metal panel. This makes a gas-tight connection to the nut and another gas-tight connection to the panel (and locks the nut). (The tightened nut makes a gas-tight connection to the bolt.) There are lots of other configurations. The principle is to establish the current path, and then use star lock washers to establish gas-tight connections. According to the research paper in Ted Eckert’s message, the star washer will cut through the paint and establish a gas-tight connection. There is no need to remove paint. Best regards, Rich From: Scott Xe <scott...@gmail.com> Sent: Friday, August 10, 2018 9:54 AM To: ri...@ieee.org; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] External toothed star washer used in earth connection Hi Rich, Thanks for your advice! 😊 Regarding the flat washer, can it be the flat ring lug of the connecting wire instead? Between the screw head and the metal enclosure, do we need a flat washer? That is to say: screw head -> flat washer -> metal enclosure -> on other side of metal enclosure with paint removed in the contact area with the flat ring lug -> flat ring lug of the earthing wire -> split ring lock washer -> plain nut to establish a good electrical earth connection. Thanks and regards, Scott Sent from Mail for Windows 10 From: Richard Nute Sent: Friday, 10 August 2018 03:11 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] External toothed star washer used in earth connection "The lock washer should not interface between the bolt head and the metal, the lock washer should be between the head and a flat washer." That locks the bolt to the flat washer so they turn together. 😊 Establishes a good electrical connection between the bolt and the flat washer! 😊 Rich - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
